1. Field of Invention
This invention relates to containers made of polymeric materials that prevent premature polymerization of 1,1-disubstituted ethylene monomer compositions. In particular, this invention relates to containers made of halogenated polymeric materials that are free from mold release agents such as zinc stearate. The present invention also relates to methods of manufacturing such containers, and methods of storing polymerizable compositions in such containers to provide an extended shelf-life to the compositions.
2. Description of Related Art
Containers made of polymeric materials are well known in the art. For example, containers made of polyolefins, such as polyethylene (PE), polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene, polyvinylchloride (PVC), and thermoplastic elastomer are widely used. Similarly, fluorocarbons, such as Halar® ethylene-chlorotrifluoroethylene copolymer (ECTFE) (Allied Chemical Corporation, Morristown, N.J.), Tefzel® ethylene-tetrafluoroethylene (ETFE) (E.I. duPont de Nemours and Co. Wilmington, Del.), tetrafluoroethylene (TFE), polytetrafluoroethylene (PTFE), polytetrafluoroethylene fluorinated ethylene propylene (PTFE-FEP), polytetrafluoroethylene perfluoroalkoxy (PTFE-PFA), and polyvinylidene fluoride (PVDF) are used as container materials. Further, engineered resins, such as polyamide (e.g. nylon), polyphenylene oxides, and polysulfone, are also used as container materials.
In choosing a suitable container for a particular application, its chemical and physical properties in relationship to the properties of its contents as well as its cost are among primary considerations. The polymeric material used to form the container must be essentially inert with respect to the composition to be contained during the period in which the composition is contained. That is, the polymeric material used to form the container must not substantially react with or catalyze reaction of the material contained in the container, preferably over at least an intended life (or shelf-life) of the material. The polymeric material must also provide adequate physical containment and protection during the period in which the composition is contained. For example, in biological research settings, containers are often selected for their ability to stably contain aqueous compositions intended for culturing of microorganisms. In chemical and industrial settings, containers that show high resistance to attack and/or degradation by chemicals, such as acids, bases, solvents, and organics, are widely used.
For example, U.S. Pat. Nos. 5,691,016 and 5,770,135 to Hobbs et al. disclose containers that are resistant to permeation by hydrocarbon fuels, and methods for producing these containers. The patents disclose a process for producing fluorinated plastic containers with excellent resistance to permeation by hydrocarbon fuels. The process relies on blow molding of plastic containers in the presence of fluorine-containing gases. In the process, a parison is formed from a pre-heated thermoplastic material, expanded within a closed mold by means of an inflating gas, and subjected to multiple fluorination treatment steps to effect fluorination of the interior surface of the parison. The containers so made show resistance to permeation by hydrocarbon fuels, such as motor oil.
Furthermore, it was known to form containers from materials that provide barrier properties. Fluoropolymers are known for such use. For example, U.S. Pat. No. 5,016,784 to Batson discloses an applicator syringe for containing and dispensing moisture-sensitive adhesive. The syringe comprises a generally sealed barrel containing a plunger having a non-stick polymeric seal and a hydrocarbon grease disposed between the seal and the adhesive contained in the barrel. The barrel is made of non-reactive fluoropolymer such as poly(monochlorotrifluoroethylene). The non-stick polymeric seal is also made of a fluoropolymer selected from polytetrafluoroethylene, polychlorotrifluoroethylene, fluorinated ethylene propylene polymers, and polyvinylidene fluoride. The moisture sensitive adhesive is generally described as a cyanoacrylate adhesive.
Similarly, U.S. Pat. Nos. 5,855,977 and 5,827,587, both to Fukushi et al., disclose multilayer articles comprising a non-fluorinated layer and a fluorinated layer. In U.S. Pat. No. 5,855,977, the multi-layer article comprises a non-fluorinated layer; a fluorinated layer including inter-polymerized monomeric units derived from hexafluoropropylene or tetrafluoroethylene, one or more non-fluorinated olefinically unsaturated monomers, and substantially no vinylidene fluoride; and an aliphatic di- or polyamine to increase adhesion between the two layers. In U.S. Pat. No. 5,827,587, the multi-layer article includes a first layer and a second layer. The first layer is a fluoropolymer comprising interpolymerized units derived from vinylidene fluoride; the second layer is a hydrocarbon polymer comprising polyamide, polyimide, carboxyl anhydride, or imide functional polyolefin; and an aliphatic di- or polyamine to increase adhesion between the two layers. The articles of both patents are disclosed as useful for tubing and hoses suitable for use in motor vehicles, such as for fuel-tank hoses.
Adhesives can comprise either organic or inorganic compounds, or a combination of the two, and have broad utility in both industrial (including household) and medical applications. Because it is most economical for manufacturers to produce adhesives on a large scale, and for merchants to purchase adhesives in bulk quantities prior to sale to consumers, adhesives are often stored for extended periods of time between manufacture and use. Therefore, they must be stored in containers that are capable of maintaining them in a substantially unadulterated state for a reasonable amount of time in order to make their bulk manufacture and purchase economical. Reasonable storage times apply to containers holding large volumes (such as greater than one liter), which are typically purchased by industrial concerns, as well as those holding small volumes (such as one liter or less, even a few milliliters or less), which are typically purchased by medical and individual consumers.
In addition to the widespread use of adhesives in industrial applications, recently the medical profession (including veterinary medicine) has begun to use certain adhesives as replacements for, or adjuncts to, sutures and staples for closure of wounds, as biological sealants, and as wound coverings. Among the adhesives currently being used for medical purposes are adhesives formed from 1,1-disubstituted ethylene monomers, such as the α-cyanoacrylates. Typically, for medical purposes, an adhesive should have a shelf-life of at least one year and preferably at least two years; however, an increased shelf-life beyond this provides increased economic advantages to both the manufacturer and the consumer. As used herein, shelf-life refers to the amount of time the container and composition therein can be held at approximately room temperature (21-25° C.) and moisture level (about 40-60% relative humidity) without degradation of the composition and/or container occurring to the extent that the composition and container cannot be used in the manner and for the purpose for which they were intended. Thus, while some degradation to either or both of the composition and container can occur, it must not be to such an extent that the composition and/or container is no longer useable. Shelf-life can thus be limited by physical or aesthetic changes to the containers or products contained therein, by chemical reactions occurring within the composition being stored, by chemical reactions between the container and the composition being stored, by degradation of the container itself, and the like.
Because the α-cyanoacrylates have become the most widely used adhesives for medical applications, containers that can hold these adhesives for extended periods of time without loss of the expected qualities of the adhesive (adherence, cure time, biological safety, purity, etc.) are essential.
High-density polyethylene (HDPE) or aluminum tubes have become the industry standard materials for packaging and containing α-cyanoacrylate adhesive monomers. HDPE generally has a density of above about 0.94 g/cm3. HDPE is the primary choice for a container material in the industry because it provides adequate containment and shelf-life for many α-cyanoacrylate monomer compositions, including methyl-, ethyl-, and butyl-cyanoacrylate monomers. These lower alkyl chain length α-cyanoacrylate adhesive monomers can be stably contained in HDPE containers for over one year without significant degradation of the monomer composition or the container.
For example, U.S. Pat. No. 4,685,591 to Schaefer et al. discloses a multilayer packaging tube suitable for holding products containing substantial fractions of cyanoacrylate-type components. The tube has a layer of high-density polyethylene positioned on the side of the tube that comes into contact with the cyanoacrylate. The high-density polyethylene preferably has a density of at least 0.950 g/cm3. A primer layer of polyethylene imine is located outside of the high density polyethylene layer and acts to block migration to the outside surface of any cyanoacrylate product that passes through the high density polyethylene.
U.S. Pat. Nos. 4,777,085, 4,731,268, and 4,698,247 to Murray, Jr. et al. disclose a multiple layer packaging sheet material, and containers and packages made therefrom, that are suitable for holding products containing substantial fractions of cyanoacrylates. The multiple-layer packaging sheet material has a layer of high-density polyethylene that is in contact with the cyanoacrylate-containing product. The high-density polyethylene preferably has a density of at least 0.950 g/cm3. The multiple-layer packaging sheet material also has a primer layer made of a low permeability polymer such as polyethylene imine (PEI) that impedes the migration of the cyanoacrylate product through the material.
U.S. Pat. No. 3,523,628 to Colvin et al. discloses a container to hold cyanoacrylate ester adhesives. The container has a body that is substantially impermeable to air and moisture to minimize deterioration of the contained adhesive, and has an opening formed of a thermoplastic resin characterized by a low surface free energy. The container body may be constructed of any air or vapor impermeable material, including metals, glass, or ceramics. Synthetic resins can be employed as the container material or as a coating on the internal surfaces of a container formed of some other material, provided the resin is selected to satisfy the critical requirements of the invention as regards air and vapor permeability and inertness with respect to initiation of polymerization of the cyanoacrylate monomers. Preferred thermoplastic resins are the halogenated hydrocarbon polymers, especially where the halogen is fluorine, such as polyhexafluoropropylene, polytetrafluoropropylene, polyvinyl fluoride, and polyvinylidene fluoride. Copolymers of ethylene with polymers of the type just named can also be used. The cyanoacrylates to be contained include alkyl cyanoacrylates with alkyl groups having from 1 to 16 carbon atoms. Lower alkyl groups, such as methyl, are preferred.
U.S. Pat. No. 3,524,537 to Winter discloses a hermetically sealed package comprising a poly(monochlorotrifluoroethylene) container having therein a sterile 2-cyanoacrylic ester adhesive. The adhesive is selected from alkyl 2-cyanoacrylate and fluoroalkyl 2-cyanoacrylate. Similar to the packages of Colvin, these packages are made from pre-fluorinated materials, and particularly from fluoropolymers.
Copending U.S. patent application Ser. No. 09/430,289 describes a container for storing a 1,1-disubstituted ethylene monomer composition. The container is comprised of a polymeric resin matrix including at least one post-halogenated or functionalized polymeric material. The post-halogenated or functionalized polymeric resin matrix provides a barrier layer to decrease permeation of the monomer composition and provides an increased stabilizing effect to the monomer composition to increase the shelf-life of the container and composition.
It is also generally known in the art to use containers that are free of undesirable additives that may affect the stability of a cyanoacrylate adhesive to be contained in the container. For example, JP 60-72945 discloses a polyethylene container that is free from stearic acid metallic salts, due to the effect of such salts on the viscosity of the cyanoacrylate adhesive. Similarly, JP 1-02026 discloses a container made of polypropylene that is free of additives other than phenolic antioxidants and acylic additives. JP 5810571 discloses a polyethylene container that is cleaned subsequent to manufacture to remove impurities associated with lubrication or polymerization catalysis. However, these references fail to recognize a direct effect caused by specific additives in specific product configurations.